What is the best way to keep your MySQL credentials private in PHP?

Question

When it comes to programming your web application in php, what is the most efficient way to prevent your MySQL information from being disclosed or discovered by another person (

Answer 1

I cannot say if this is the best, but this is how I do it;

I have a config.php file, which holds my DB connection credentials, and is not directly accessible. I have a DB class which requires the config.php to make the connection, and I have a site class which extends the DB class.

This is a very common way of doing things, and is generally accepted.